Refrigerator car



B. E. WILLIAMS REFRIGERATOR CAR Filed May 3, 194

IN V EN TOR.

fleuerrfl @ZYY/lhma Patented Sept. 5, 1950 REFRIGERATOR CAR,

Beverly E. Williams, Chicago, Ill., assignor, by

mesne assignments, to Swift & Company, Chicago, 111., a corporation of Illinois Application May 3, 1947, Serial No. 745,747

20 Claims.

This invention relates to the refrigerating art and more particularly to a method and means for controlling the temperature of the lading storage space in a railroad refrigerator car, refrigerated transit van, or like refrigerated transportation unit.

It is an object of this invention to provide improved means and method for storing perishables.

Another object of this invention is to provide an improved wall structure for enclosing a storage space for perishable products.

A further object of this invention is to provide an improved refrigerating wall structure for cooling perishable products and method for using the wall.

Still another object of this invention is to provide improved means for cooling the lading storage space in transportation units such as railroad rolling stock, transit or lift vans, and the like.

Another object is to provide an improved method and means for maintaining a substantially constant and uniform temperature within such a transportation unit.

Another object of this invention is to provide an improved method for cooling the walls of a portable storage space for perishable products and maintaining a low temperature within the space defined by the walls.

Another object of this invention is to provide an improved method for chilling the lading held in a storage space.

Other objects will appear from the specification below.

In the drawings,

Figure 1 is a sectional side elevation of a transportation unit body having the improved wall structure of this invention;

Figure 2 is a sectional perspective View of a section of the Wall of the unit showing a louver arrangement over the face of the wall; and

Figure 3 is a sectional plan view of a modified wall structure for such a unit.

For many years the conventional means for transporting perishable products in railroad cars has been the heavily constructed refrigerator car carrying ice bunkers at the ends. To provide insulation and in order to carry a sufficient quantity of ice and brine to maintain the desired low temperature in the lading storage space, an unusually heavy car structure is required. Because of the heavy construction it is necessary to move such cars in slow moving trains and in addition, because of the relatively inefiicient insulation found in the conventional heavily constructed car, it is frequently necessary that the conventional cars be reiced before a trip is completed. To accomplish this, the ice bunkers must be. drained of the brine solution resulting from the melting of ice with salt and a new charge of frozen;

5 ice and salt placed in the bunkers. The present-g day practice followed in the reicing of the car requires that it be released from themoving train and delivered to the icing station,- where it must stand until the reicing has been completed and it is again worked into the moving freight train schedule. 1 v I The delays caused by the slower maneuver-: ability of the heavily constructed conventional car and that resulting from the necessity for re-,

icing the bunkers to maintain the propertemperatures are costly and should be eliminated. For example, it not infrequently requires three. to four days to transport a refrigerator car loaded. with meat from Chicago to New York city. 0n.

the other hand, this is merely a fast overnight run for the through passenger trains and fast express schedules. i j

The slow speed characteristics of the conven-* tional refrigerator car is an objectionable feature in itself, but when considered more particularly:

in conjunction with the demands of the presentday food industry, wherein frozen foods are becoming more and more popular, it is. essential;

that improved transportation means be provided Not only is it desirable that the distribution'of perishables be speeded up, but frozen'foods must be stored at lower temperatures than are usual and, furthermore, the temperature must beheld more nearly constant in order to avoid deteriora- 5 tion of the frozen goods.

The handling of frozen foods is a relatively delicate matter and it has been noted that even' the ordinary changes in atmospheric conditions have a decided effect on their condition. These 40 variations of temperature, pressure, and humid'-.

ity produce an effect called barometric pumping which causes the air inside a package to be. exchanged for air outside of the package. tends to dehydrate the product and sometimes produces a shrinkage amounting to as much as L per cent of the weight of the product. Fruits and vegetables are particularly susceptible to damage of this type. This barometric pumping action is not limited to the interchange of air in individual packages of food products, but is a 5 encountered in using the conventional. refriger-..

This

ator cars and also to improve the conditions under which a perishable product may be transported in railroad cars and other form of transporting means. In following the practice of this teaching, the delays and labor required to service a conventional refrigerator car are substantially eliminated, resulting in the more efficient use of railroad equipment and distribution of perishable products. The invention of this disclosure makes it feasible to process a perishable product at a central point in the farming areas, freeze it and ship it to the points of consumption more rapidly and with less loss than has ever been possible in the past. And more especially, in using the herein-disclosed structure and with the speed-up in transportation which can be accomplished, the deficiencies of the prior art means are substantially eliminated.

This invention carries forward the original teaching of Williams patent, No. 2,381,796, dated A Augustfl, 1945, making use in part of the principles ofthe Williams car and adding thereto a more efficient wall structure to maintain the temperature within the lading storage space and having improved sources of refrigeration to provide additional cold as the unit is in'transit.

The present invention provides a unit body havingan: outer layer of thermal insulation which maybe of any conventional sort, such as rock wool, fibre glass, foam glass, vermiculite, expanded nylon, etc., coupled with an inner hollow wall-structure taking the form of a plurality of separate tanks or containersarranged in side by" side relationship. Certain of the tanks form channels through which heat exchange medium maybe circulated to chill the loaded unit, such as 'a:cold.liquid or an expanding gas. Thereafter'these tanks'may be connected to vacuumproducing means and evacuated'to provide additional insulation as disclosed insaid Williams patent.v

Where the heat exchange medium takes the form of an expanding gas, the last mentioned wall tanks may: be'provided with expansion valves 'so that a suitable refrigerant may be driven into the tank and expanded in two stages, first into the tank and then directly into the lading storage: space. The refrigerant is then at least partially evaporated in the immediate proximity of the product.

Positioned at spaced intervals between the above-described tanks are a series of tanks that are preferably maintained full of an eutectic solution, and the refrigerant flowing in the'firstmentioned tanks may be directed against a portion'of the outer surfaces of these filled tanks to freeze the eutectic solution. The eutectic solution held in these spaced tanks is frozen, so that during the periods when the refrigerant supply-is cut off, the temperature of the lading storage space will bemaintained substantially constant at the melting point of the eutectic solution. Every other channel can conveniently bemade into an eutectic storage chamber, thus providing a relatively large wall space packed with frozen eutectic, whereby a greatly enlarged cold wall surface is provided so that the fluctuation of the temperature inside the product storage chamber is substantially eliminated. Further, the particular eutectic solution may be selected to have a melting point close to the desired temperature to be maintained in the lading. storage space and the same constant meltingltemperature prevails at all times until the eutectic solution is substantially all melted since it is not diluted by the melting of any ice as is the case of the conventional brine cooling system.

A preferred form embodying this invention is disclosed in the drawings, and the outer shell ID of the wall structure, as above stated, may be packed with any suitable insulation. Fibre glass, spun glass, vermiculite, spun nylon and foam glasshave been found to be quite satisfactory, since they are quite inert, waterproof, vermin-proof, and do not absorb odors. The thickness of the shell is preferably maintained at about two inches, and a certain amount of heat can be turned away from the car by providing a surface of reflecting material on the outside of the car body, and, conversely, heat may be extracted rapidly from products held in the lading storage space by using a dull surface on all the walls of the shell structure facing inwardly toward the lading.

Tanks to receive the refrigerant and eutectic solution are positioned inside the shell, the tanks, for example, being best shown as H, I2, [3, l4, and I5 in Figure 1. The tanks are substantially rectangular in cross section and are arranged side by side with their adjacent surfaces juxtaposed in good heat exchange relationship. As shown, alternate tanks l2 and M are adapted to be filled with an eutectic solution, and the other tanks II, l3, l5, etc., are designed to serve alternately as refrigerant and vacuum chambers.

In certain cases the wall tanks may all be selectively connected to a refrigerant supply or vacuum producingv means. In any event, the vacuum connection with the tanks is preferably made at the bottom through a centralheader 20, positioned in the floor of the car, the header having an outlet pipe 2| connected between it and the vacuum producing means 22. The vacuum pump may be any conventional type and may be driven from the axle of the car, or connected with the power plant of an auto truck, or may be plugged into the power line at a loading platform.

The containers or wall tanks that are connected to the refrigerant supply are coupled at the top to a refrigerant supply header 25 through individual inlet means 26 connected between the supply header 25 and each of the tanks. A refrigerated brine solution, such as calcium chloride, or other heat transmission liquid, such as tetracresylsilicate, may be circulated through these tanks to cool the unit and freeze the eutectic solution, and then withdrawn to the refrigeration source through a valve-controlled outlet 26' in line 2|; or liquid carbon dioxide or any other refrigerant that expands to an inert gas form may be supplied for expansion through valves 21 into the wall tanks. Provision may also be made to expand this last-mentioned type of refrigerant at a lower pressure into the lading space, and in this case the wall tanks II, l3, and I5 must be provided with additional conventional expansion valves. As shown in the drawings, expansion valves 21 are positioned at the inlets to these tanks to control the expansion of such'a refrigerant into the wall tanks, and if it is desired to further expand the refrigerant from the wall tanks into the lading storage space, a plurality of expansion valves 30 may be provided on the face of each tank.

In order to obtain a more prolonged refrigerating or holdover effect, alternate tanks will usually be filled with brine or eutectic solution which is frozen by circulation of the cold heat transfer medium, such as tetracresylsilicate, or by theexpansion of a refrigerant in the remaining alternate tanks as described above. If a refrigerant of the latter type is also expanded directly into' the lading storage space, part of it may be blown across the faces of the brine or eutectic containing tanks being chilled to more quickly extract the heat from the tanks to freeze the brine or eutectic solution. After the car has been loaded and the brine has been frozenin all of the tanks, the car is then ready to travel and may be connected to a train.

Tetracresylsilicate is mentioned as an example of the class of tetra-aryl silicates disclosed for use as liquid heat exchange media in U. S. Patent to Lotte I-I. Johnston, No. 2,335,012, dated November 23, 1943. Any other suitable type of liquid heat exchange medium may be used.

The initial chilling and freezing of the brine in the wall tanks may be accomplished at a central servicing station where refrigerating means are readily available. In transit, the brine solution in the tanks slowly melts and maintains the desired inside temperature and, due to the large surface area exposed, a much more constant low temperature condition is maintained throughout the entire lading area than has ever been possible with the older ice bunker structure heretofore used.

In cases where the outside ambient temperature is lower than the temperature desired to be maintained within the lading storage space, the temperature control medium may be substantially higher in temperature than theoutdoor temperature, but the temperature of the. control medium, such as brine or tetracresylsilicate is calculated and regulated to be such as to give the desired temperature result to both the walls of the car or van and also to the lading interior and to the product itself.

When using the above described structure, the alternate tanks used for the refrigerant may subsequently be vacuumized after the car has been serviced so that a composite wall structure results which has a much lower coefficient of heat transfer. The lading storage space is then protected against heat transfer by the outer layer of insulation and an inner layer substantially equal to the thickness of the wall tanks and comprising sections that are either vacuumized or filled with frozen eutectic.

As shown in Figure 2, the lading storage space is preferably separated somewhat from the wall of the car by a suitable louvered bulkhead means 4E3. The bulkheads are spaced slightly from the wall tanks to form a temperature equalizing air space so that inequalities in wall surface temperatures may be leveled out by the resulting convection currents that are set up within this space between the walls and the louvers, and further, the production of these ajlr currents tends to eliminate the drying of the air by condensation of. moisture on said walls. This ensures that the temperature of the storage space will be maintained substantially con-- stant and the relative humidity maintained at a high per cent.

If the transporting means. should be unduly delayed in transit and it is desired to again cool the lading or refreeze the brine in the wall tanks during shipments, the headers 25 and 20 can be readily reconnected to a refrigerant supply and vacuumizing means in a simple servicing. operation, or a supply of compressed liquefied re frigerant mayibe carried in orunderthe unit (ill and released by automatic meansv to be expanded.

through the empty wall tanks or directly into the lading storage space and against the wall of the brine tanks within the temperature equalizing space between the walls and the louvers. Any suitable thermostatic control means may be used to release the refrigerant as desired.

Figure 3 shows a modified tank wall structure. This structure provides a maximum surface for exposure of the frozen eutectic to the lading storage space and the refrigerant circulating passage, but has a minimum of the frozen eutectic surface area exposed to the warmer outside surface of the car. The wall between the eutectic cham-' her and the refrigerating chamber may be corrugated to provide an increased proportion of surface area between the tanks for heat transfer, or fins 5| of heat-conductive material may be used if an even faster heat transfer is desired. With this structure, it is apparent that only a small area of the frozen eutectic solution is exposed to the normally warmer outside insulated surface, and any heat flowing to the inside of the unit by conduction must move along the extended path formed by the common wall between the refrigerant chamber and the eutectic chamher, which wall borders the frozen eutectic whereby the heat is substantially dissipated. The wall structure for a refrigerated transporting means, described above may be used for all the purposes of the Williams car and in use will be found to have provision for more efllcient control of the temperature of the storage space. The use of frozen brine or other eutectic solution in alternate wall tanks serves to even out nearly all of the temperature variations which would otherwise be encountered, and distribution of these tanks throughout the length of the car makes for a more even distribution of the weight so that lighter car structures can be made. With the m0re efiicient insulation provided by this structure additional weight is elminated. The same advantages are obtained when the invention is'used in other transportation units, such as transit or lift vans.

- Such units may be cooled and loaded at a central point in the packing plant or other processing factory, orin farm-producing areas, etc. After-the chilled product has been placed in the unit, it is sealed and finally chilled to the desired temperature with freezing of the brine tanks (if they are being used); The refrigerant supply means is then disconnected and the refrigerant withdrawn and a vacuum drawn on the remaining walltanks. The unit is then ready for transportation, and because of its very light-weight construction and because of the elimination of the necessity of icing in transit, the loaded unit may be delivered rapidly from the loading point to the consumer. In the case of railroad cars,

ii} the lighter weight structure makes it possible to couple a car full of frozen food products to the faster moving trains, and the product may be delivered to the consumer much more quickly and, therefore, with less likelihood of damage. In the case of portable units, such as transit or price of various products to deteriorate, are

largely eliminated. Also, the more even temperature conditions minimize the damage inherent in the barometric pumping process mentioned above. With this structure, by properly proportioning the size and structure of the wall tanks, the quantity of frozen brine or eutectic required to hold a given temperature may be provided to produce the optimum conditions for transporting a frozen product under constant and appropriate temperature conditions.

The structure described above may be built into railroad cars, trailer truck arrangements, or unit structures adapted to be carried on trucks or flat cars or for shipments in airplane or maritime freight, and hence may be used under widely varying conditions. It isthus conceivable that many modifications of this invention will occur to those skilled in the art, which will fall within the scope of the following claims.

I claim 1. The method of refrigerating a transportation unit, including a wall having compartments containing liquid to be frozen and adjacent refrigerating sections, which comprises freezing the liquid in said compartments and chilling said sections and the lading space by circulating a cold heat exchange medium in said sections,.and then stopping the circulation of said medium and disconnecting said sections from the supply thereof for subsequent transit of said unit, during which the low temperature within the unit is maintained by the melting of the frozen liquid in said compartments.

2. The method defined in claim 1, wherein said liquid is a eutectic solution having a freezing point at approximately the maximum temperature to be maintained in said storage space.

3'. The method defined in claim 1, wherein said medium is a cold liquid and wherein said liquid medium is withdrawn from said sections prior to subsequent transit.

4. The method defined in claim 3, wherein said medium is calcium chloride brine.

5. The method defined in claim 3, wherein said medium is tetra-arylsilicate.

6. The method defined in claim 3, whereinsaid sections are vacuumized and closed after the liquid medium is withdrawn therefrom.

"I. The method defined in claim 1, wherein said medium comprises a normally gaseous refrigerant that is expanded into said refrigerating sections.

8. The method defined in claim 7, wherein said gaseous refrigerant is also expanded into the lading space.

9. In a refrigerated transportation unit, a wall structure enclosing the lading storage space and comprising a plurality of compartments, certain of said compartments containing a liquid to be frozen and being in heat exchanging relationship with the rest of the compartments, and means for circulating a heat exchange medium through the rest of the compartments to chill the wall and lading storage space and freeze said liquid.

10. In a refrigerated transportation unit, a wall structure enclosing the lading storage space and comprising a plurality of compartments, certain of said compartments containing a liquid to be frozen and being in heat exchanging relationship with the rest of the compartments, means for circulating a heat exchange medium through the rest of the compartments to chill the wall and lading S o e space and freeze said liquid, and louvered bulkheads spaced from the inner 8. surfaces of said compartments and defining the lading storage space.

11. In a refrigerated transportation unit, a wall structure enclosing the lading storage space and comprising an outer layer of insulation and an inner layer composed of a plurality of compartments, certain of said compartments containing a liquid to be frozen and being in heat exchanging relationship with the rest of the compartments, and means for circulating a heat exchange medium through the rest of the compartments to chill the wall and lading storage space and freeze said liquid.

12. In a refrigerated transportation unit, a Wall structure enclosing the lading storage space and comprising an outer layer of insulation and an inner layer composed of a plurality of compartments, certain of said compartments containing a liquid to be frozen and being in heat exchanging relationship with the rest of the compartments, means for circulating a heat exchange medium through the rest of the compartments to chill the wall and lading storage space and freeze said liquid and louvered bulkheads spaced from the inner layer and defining the lading storage space.

13. In a refrigerated transportation unit, a wall structure enclosing the lading storage space and comprising a plurality of compartments arranged substantially in a side by side heat exchanging relationship one with another, header means for supplying a liquid to be frozen to certain of said compartments, and header means for circulating a heat exchange medium through the rest of the compartments to chill the wall and lading storage space and freeze said liquid.

14. In a refrigerated transportation unit, a wall structure enclosing the lading storage space and comprising an outer layer of insulation and an inner layer composed of compartments arranged substantially in a side by side heat exchanging relationship, header means for supplying a liquid to be frozenv to certain of said compartments, and header means for circulating a heat exchange medium through the rest of the compartments to chill the wall and lading storage space and freeze said liquid.

15. In a refrigerated transportation unit, a wall structure enclosing the lading storage space and comprising an outer layer of insulation and an inner layer composed of compartments arranged substantially in a side by side heat exchanging relationship, header means for supplying a liquid to be frozen to certain of said compartments, header means for circulating a heat exchange medium through the rest of the compartments to chill the wall and lading storage space and freeze said liquid, and louvered bulkheads spaced from said inner layer and defining the lading storage space.

16. In a refrigerated transportation unit, a wall structure enclosing the lading storage space and comprising an outer layer of insulation, the sides at least of said wall structure having an inner layer composed of a plurality of vertical compartments arranged side by side in heat exchange relationship, inlet and outlet connections at the top and bottom of each compartment, header means for supplying a liquid to be frozen through said connections to certain of said compartments, and header means for circulating a heat exchange medium through said connections to the rest of the compartments to chill the wall and lading storage space and freeze said liquid.

17. In a refrigerated transportation unit, a wall structure enclosin the lading storage space and comprising an outer layer of insulation, the sides at least of said wall structure having an inner layer composed of a plurality of vertical compartments of substantially rectangular cross section arranged side by side with their adjacent surfaces juxtaposed in heat exchange relationship, inlet and outlet connections at the top and bottom of each compartment, header means for supplying a liquid to be frozen through said connections to certain of said compartments, and header means for circulating a heat exchange medium through said connections to the rest of the compartments to chill the wall and lading storage space and freeze said liquid.

18. In a refrigerated transportation unit, a wall structure enclosing the lading storage space and comprising an outer layer of insulation, the sides, at least, of said wall structure having an inner layer composed of a plurality of vertical compartments of substantially rectangular cross section arranged side by side with their adjacent surfaces juxtaposed in heat exchange relationship, inlet and outlet connections at the top and bottom of each compartment, header means for supplying a liquid to be frozen through said connections to certain of said compartments, header means for circulating a heat exchange medium through said connections to the rest of the compartments to chill the wall and lading storage space and freeze said liquid, and louvered bulk- 10 heads spaced from said inner layer and defining the lading storage space.

19. A wall structure for surrounding the lading storage space in a refrigerator means comprising a hollow partition formed of a plurality of compartments arranged substantially side by side, certain of said compartments having an eutectic solution sealed therein, the remainder of said compartments being adapted for the expansion of a refrigerant, means to supply a compressed but normally gaseous refrigerant, and expansion valve means to initially expand said refrigerant into said remaining chambers and additional expansion valve means to permit further expansion of said refrigerant into the lading storage space to fiow across the face of said certain compartments.

20. In a refrigerated transportation unit, a wall structure enclosing the lading storage space and comprising a plurality of compartments, said compartments being generally trapezoidal in their transverse cross section, certain of said compartments containing a liquid to be frozen, said certain compartments being disposed so that the Wider bases of their said transverse cross sections are disposed adjacent said space, and means for circulating a heat exchange medium through the rest of the compartments to chill the wall and lading storage space and freeze said liquid.

BEVERLY E. WILLIAMS.

No references cited. 

